Add group: edge to .travis.yml
Add group: edge to .travis.yml

Travis recommends that we do this before tomorrow:
https://blog.travis-ci.com/2017-06-19-trusty-updates-2017-Q2.

Signed-off-by: mulhern <7b51bcf507bcd7afb72bf8663752c0ddbeb517f6@redhat.com>

trgill/stratisd,mulkieran/stratisd,stratis-storage/stratisd,stratis-storage/stratisd,mulkieran/stratisd,trgill/stratisd,stratis-storage/stratisd